[libc][stdfix] Implement countlsfx functions in libc. (llvm#126597)

fixes llvm#113357 --------- Signed-off-by: krishna2803 <[email protected]>
joaosaffran · Feb 14, 2025 · f897c75 · f897c75
1 parent c3d6359
commit f897c75
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Showing 48 changed files with 919 additions and 27 deletions.
diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
@@ -469,6 +469,18 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
     libc.src.stdfix.ukbits
     libc.src.stdfix.lkbits
     libc.src.stdfix.ulkbits
+    libc.src.stdfix.countlshr
+    libc.src.stdfix.countlsr
+    libc.src.stdfix.countlslr
+    libc.src.stdfix.countlshk
+    libc.src.stdfix.countlsk
+    libc.src.stdfix.countlslk
+    libc.src.stdfix.countlsuhr
+    libc.src.stdfix.countlsur
+    libc.src.stdfix.countlsulr
+    libc.src.stdfix.countlsuhk
+    libc.src.stdfix.countlsuk
+    libc.src.stdfix.countlsulk
   )
 endif()
 

diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
@@ -464,6 +464,18 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
     libc.src.stdfix.ukbits
     libc.src.stdfix.lkbits
     libc.src.stdfix.ulkbits
+    libc.src.stdfix.countlshr
+    libc.src.stdfix.countlsr
+    libc.src.stdfix.countlslr
+    libc.src.stdfix.countlshk
+    libc.src.stdfix.countlsk
+    libc.src.stdfix.countlslk
+    libc.src.stdfix.countlsuhr
+    libc.src.stdfix.countlsur
+    libc.src.stdfix.countlsulr
+    libc.src.stdfix.countlsuhk
+    libc.src.stdfix.countlsuk
+    libc.src.stdfix.countlsulk
   )
 endif()
 

diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
@@ -749,6 +749,18 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
     # TODO: https://github.com/llvm/llvm-project/issues/115778
     libc.src.stdfix.lkbits
     libc.src.stdfix.ulkbits
+    libc.src.stdfix.countlshr
+    libc.src.stdfix.countlsr
+    libc.src.stdfix.countlslr
+    libc.src.stdfix.countlshk
+    libc.src.stdfix.countlsk
+    libc.src.stdfix.countlslk
+    libc.src.stdfix.countlsuhr
+    libc.src.stdfix.countlsur
+    libc.src.stdfix.countlsulr
+    libc.src.stdfix.countlsuhk
+    libc.src.stdfix.countlsuk
+    libc.src.stdfix.countlsulk
   )
 endif()
 

diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
@@ -875,6 +875,18 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
     libc.src.stdfix.ukbits
     libc.src.stdfix.lkbits
     libc.src.stdfix.ulkbits
+    libc.src.stdfix.countlshr
+    libc.src.stdfix.countlsr
+    libc.src.stdfix.countlslr
+    libc.src.stdfix.countlshk
+    libc.src.stdfix.countlsk
+    libc.src.stdfix.countlslk
+    libc.src.stdfix.countlsuhr
+    libc.src.stdfix.countlsur
+    libc.src.stdfix.countlsulr
+    libc.src.stdfix.countlsuhk
+    libc.src.stdfix.countlsuk
+    libc.src.stdfix.countlsulk
   )
 endif()
 

diff --git a/libc/docs/headers/math/stdfix.rst b/libc/docs/headers/math/stdfix.rst
@@ -73,7 +73,7 @@ The following functions are included in the ISO/IEC TR 18037:2008 standard.
 +---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
 | \*bits        |                |             |               |            |                |             |                |             |               |            |                |             |
 +---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
-| countls       |                |             |               |            |                |             |                |             |               |            |                |             |
+| countls       | |check|        | |check|     | |check|       | |check|    | |check|        | |check|     | |check|        | |check|     | |check|       | |check|    | |check|        | |check|     |
 +---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
 | divi          |                |             |               |            |                |             |                |             |               |            |                |             |
 +---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+

diff --git a/libc/include/stdfix.yaml b/libc/include/stdfix.yaml
@@ -306,3 +306,87 @@ functions:
     arguments:
       - type: unsigned int
     guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlshr
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: short fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlsr
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlslr
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: long fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlshk
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: short accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlsk
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlslk
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: long accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlsuhr
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: unsigned short fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlsur
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: unsigned fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlsulr
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: unsigned long fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlsuhk
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: unsigned short accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlsuk
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: unsigned accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: countlsulk
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: unsigned long accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
diff --git a/libc/src/__support/fixed_point/CMakeLists.txt b/libc/src/__support/fixed_point/CMakeLists.txt
@@ -19,6 +19,7 @@ add_header_library(
     libc.src.__support.macros.optimization
     libc.src.__support.CPP.type_traits
     libc.src.__support.CPP.bit
+    libc.src.__support.CPP.limits
     libc.src.__support.math_extras
 )
 

diff --git a/libc/src/__support/fixed_point/fx_bits.h b/libc/src/__support/fixed_point/fx_bits.h
@@ -11,9 +11,10 @@
 
 #include "include/llvm-libc-macros/stdfix-macros.h"
 #include "src/__support/CPP/bit.h"
+#include "src/__support/CPP/limits.h" // numeric_limits
 #include "src/__support/CPP/type_traits.h"
-#include "src/__support/macros/attributes.h" // LIBC_INLINE
-#include "src/__support/macros/config.h"
+#include "src/__support/macros/attributes.h"   // LIBC_INLINE
+#include "src/__support/macros/config.h"       // LIBC_NAMESPACE_DECL
 #include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
 #include "src/__support/math_extras.h"
 
@@ -50,6 +51,12 @@ template <typename T> struct FXBits {
   static constexpr StorageType SIGN_MASK =
       (fx_rep::SIGN_LEN == 0 ? 0 : StorageType(1) << SIGN_OFFSET);
 
+  // mask for <integral | fraction>
+  static constexpr StorageType VALUE_MASK = INTEGRAL_MASK | FRACTION_MASK;
+
+  // mask for <sign | integral | fraction>
+  static constexpr StorageType TOTAL_MASK = SIGN_MASK | VALUE_MASK;
+
 public:
   LIBC_INLINE constexpr FXBits() = default;
 
@@ -74,6 +81,12 @@ template <typename T> struct FXBits {
     return (value & INTEGRAL_MASK) >> INTEGRAL_OFFSET;
   }
 
+  // returns complete bitstring representation the fixed point number
+  // the bitstring is of the form: padding | sign | integral | fraction
+  LIBC_INLINE constexpr StorageType get_bits() {
+    return (value & TOTAL_MASK) >> FRACTION_OFFSET;
+  }
+
   // TODO: replace bool with Sign
   LIBC_INLINE constexpr bool get_sign() {
     return static_cast<bool>((value & SIGN_MASK) >> SIGN_OFFSET);
@@ -163,6 +176,24 @@ template <typename T> LIBC_INLINE constexpr T round(T x, int n) {
   return bit_and((x + round_bit), rounding_mask);
 }
 
+// count leading sign bits
+// TODO: support fixed_point_padding
+template <typename T>
+LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_fixed_point_v<T>, int>
+countls(T f) {
+  using FXRep = FXRep<T>;
+  using BitType = typename FXRep::StorageType;
+  using FXBits = FXBits<T>;
+
+  if constexpr (FXRep::SIGN_LEN > 0) {
+    if (f < 0)
+      f = bit_not(f);
+  }
+
+  BitType value_bits = FXBits(f).get_bits();
+  return cpp::countl_zero(value_bits) - FXRep::SIGN_LEN;
+}
+
 } // namespace fixed_point
 } // namespace LIBC_NAMESPACE_DECL
 

diff --git a/libc/src/__support/fixed_point/fx_rep.h b/libc/src/__support/fixed_point/fx_rep.h
@@ -43,8 +43,8 @@ template <> struct FXRep<short fract> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 1;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = 0;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = SFRACT_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return SFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return SFRACT_MAX; }
@@ -63,8 +63,8 @@ template <> struct FXRep<unsigned short fract> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 0;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = 0;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = USFRACT_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return USFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return USFRACT_MAX; }
@@ -83,8 +83,8 @@ template <> struct FXRep<fract> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 1;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = 0;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = FRACT_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return FRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return FRACT_MAX; }
@@ -103,8 +103,8 @@ template <> struct FXRep<unsigned fract> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 0;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = 0;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = UFRACT_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return UFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return UFRACT_MAX; }
@@ -123,8 +123,8 @@ template <> struct FXRep<long fract> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 1;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = 0;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = LFRACT_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return LFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return LFRACT_MAX; }
@@ -143,8 +143,8 @@ template <> struct FXRep<unsigned long fract> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 0;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = 0;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = ULFRACT_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return ULFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return ULFRACT_MAX; }
@@ -163,8 +163,8 @@ template <> struct FXRep<short accum> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 1;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = SACCUM_IBIT;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = SACCUM_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return SACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return SACCUM_MAX; }
@@ -183,8 +183,8 @@ template <> struct FXRep<unsigned short accum> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 0;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = USACCUM_IBIT;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = USACCUM_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return USACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return USACCUM_MAX; }
@@ -203,8 +203,8 @@ template <> struct FXRep<accum> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 1;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = ACCUM_IBIT;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = ACCUM_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return ACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return ACCUM_MAX; }
@@ -223,8 +223,8 @@ template <> struct FXRep<unsigned accum> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 0;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = UACCUM_IBIT;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = UACCUM_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return UACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return UACCUM_MAX; }
@@ -243,8 +243,8 @@ template <> struct FXRep<long accum> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 1;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = LACCUM_IBIT;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = LACCUM_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return LACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return LACCUM_MAX; }
@@ -263,8 +263,8 @@ template <> struct FXRep<unsigned long accum> {
   LIBC_INLINE_VAR static constexpr int SIGN_LEN = 0;
   LIBC_INLINE_VAR static constexpr int INTEGRAL_LEN = ULACCUM_IBIT;
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = ULACCUM_FBIT;
-  LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
-      SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int TOTAL_LEN = SIGN_LEN + VALUE_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return ULACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return ULACCUM_MAX; }

diff --git a/libc/src/stdfix/CMakeLists.txt b/libc/src/stdfix/CMakeLists.txt
@@ -47,6 +47,18 @@ foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
       libc.src.__support.CPP.bit
       libc.src.__support.fixed_point.fx_bits
   )
+
+  add_entrypoint_object(
+    countls${suffix}
+    HDRS
+      countls${suffix}.h
+    SRCS
+      countls${suffix}.cpp
+    COMPILE_OPTIONS
+      ${libc_opt_high_flag}
+    DEPENDS
+      libc.src.__support.fixed_point.fx_bits
+  )
 endforeach()
 
 add_entrypoint_object(